Mission Statement

As part of the federal government’s National Institutes of Health (NIH), the National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.”

Autosomal Recessive Inheritance

Autosomal recessive inheritance is the most common type of inheritance for retinal dystrophies. When this type of condition is present in a family, it is often seen only in one child or in siblings, not in the parents or other relatives.

As shown in the figure, to have symptoms of BCD, an individual must have two copies of the same disease gene. We all have two copies of each gene, since we inherit one from our father and one from our mother.

In the figure above, the N stands for the normal copy of the BCD gene and the B stands for the abnormal copy of the BCD gene. Both parents have an N gene and a B gene and are therefore called “carriers.” In this scenario, there is a 75 percent chance that a child will not have Bietti’s crystalline dystrophy. In each child there is a 50 percent chance to inherit the N gene and a 50 percent chance to inherit the B gene from each parent. There is:

a 25 percent chance that a child will inherit both N genes and be unaffected

a 50 percent chance that a child will inherit one N gene and one B gene and be unaffected, but be a carrier of the mutant gene

a 25 percent chance for a child to inherit both B genes and be affected

These recessive genes can be passed on for generations without causing disease, since two copies are needed to cause symptoms.

The National Eye Institute (NEI) is part of the National Institutes of Health (NIH) and is the Federal government’s lead agency for vision research that leads to sight-saving treatments and plays a key role in reducing visual impairment and blindness.